Add readiness support to s6-svstat

3 files changed, 120 insertions, 6 deletions

diff --git a/src/supervision/deps-exe/s6-notifywhenup b/src/supervision/deps-exe/s6-notifywhenup
new file mode 100644
index 0000000..077e863
--- /dev/null
+++ b/src/supervision/deps-exe/s6-notifywhenup
@@ -0,0 +1,3 @@
+${LIBS6}
+-lskarnet
+${TAINNOW_LIB}
diff --git a/src/supervision/s6-notifywhenup.c b/src/supervision/s6-notifywhenup.c
new file mode 100644
index 0000000..98f0401
--- /dev/null
+++ b/src/supervision/s6-notifywhenup.c
@@ -0,0 +1,92 @@
+/* ISC license. */
+
+#include <unistd.h>
+#include <errno.h>
+#include <skalibs/uint.h>
+#include <skalibs/bytestr.h>
+#include <skalibs/sgetopt.h>
+#include <skalibs/strerr2.h>
+#include <skalibs/allreadwrite.h>
+#include <skalibs/tai.h>
+#include <skalibs/iopause.h>
+#include <skalibs/djbunix.h>
+#include <s6/ftrigw.h>
+#include <s6/s6-supervise.h>
+
+#define USAGE "s6-notifywhenup [ -d fd ] [ -e fifodir ] [ -f ] [ -t timeout ] prog..."
+#define dieusage() strerr_dieusage(100, USAGE)
+
+static int run_child (int fd, char const *fifodir, unsigned int timeout)
+{
+  char dummy[4096] ;
+  iopause_fd x = { .fd = fd, .events = IOPAUSE_READ } ;
+  tain_t deadline ;
+  char pack[TAIN_PACK] ;
+  if (!tain_now_g()) strerr_diefu1sys(111, "tain_now") ;
+  if (timeout) tain_from_millisecs(&deadline, timeout) ;
+  else deadline = tain_infinite_relative ;
+  tain_add_g(&deadline, &deadline) ;
+  for (;;)
+  {
+    register int r = iopause_g(&x, 1, &deadline) ;
+    if (r < 0) strerr_diefu1sys(111, "iopause") ;
+    if (!r) return 99 ;
+    r = sanitize_read(fd_read(fd, dummy, 4096)) ;
+    if (r < 0)
+      if (errno == EPIPE) return 1 ;
+      else strerr_diefu1sys(111, "read from parent") ;
+    else if (r)
+      if (byte_chr(dummy, r, '\n') < r) break ;
+  }
+  close(fd) ;
+  tain_pack(pack, &STAMP) ;
+  if (!openwritenclose_suffix(S6_SUPERVISE_READY_FILENAME, pack, TAIN_PACK, ".new"))
+    strerr_warnwu1sys("open " S6_SUPERVISE_READY_FILENAME " for writing") ;
+  ftrigw_notify(fifodir, 'U') ;
+  return 0 ;
+}
+
+int main (int argc, char const *const *argv, char const *const *envp)
+{
+  unsigned int fd = 1 ;
+  char const *fifodir = "event" ;
+  int df = 1 ;
+  unsigned int timeout = 0 ;
+  PROG = "s6-notifywhenup" ;
+  {
+    subgetopt_t l = SUBGETOPT_ZERO ;
+    for (;;)
+    {
+      register int opt = subgetopt_r(argc, argv, "d:e:ft:", &l) ;
+      if (opt == -1) break ;
+      switch (opt)
+      {
+        case 'd' : if (!uint0_scan(l.arg, &fd)) dieusage() ; break ;
+        case 'e' : fifodir = l.arg ; break ;
+        case 'f' : df = 0 ; break ;
+        case 't' : if (!uint0_scan(l.arg, &timeout)) dieusage() ; break ;
+        default : dieusage() ;
+      }
+    }
+    argc -= l.ind ; argv += l.ind ;
+  }
+  if (!argc) dieusage() ;
+
+  {
+    int p[2] ;
+    pid_t pid ;
+    if (pipe(p) < 0) strerr_diefu1sys(111, "pipe") ;
+    pid = df ? doublefork() : fork() ;
+    if (pid < 0) strerr_diefu1sys(111, df ? "doublefork" : "fork") ;
+    else if (!pid)
+    {
+      PROG = "s6-notifywhenup (child)" ;
+      close(p[1]) ;
+      return run_child(p[0], fifodir, timeout) ;
+    }
+    close(p[0]) ;
+    if (fd_move((int)fd, p[1]) < 0) strerr_diefu1sys(111, "fd_move") ;
+  }
+  pathexec_run(argv[0], argv, envp) ;
+  strerr_dieexec(111, argv[1]) ;
+}
diff --git a/src/supervision/s6-svstat.c b/src/supervision/s6-svstat.c
index 4f95a0c..de8fe0d 100644
--- a/src/supervision/s6-svstat.c
+++ b/src/supervision/s6-svstat.c
@@ -23,6 +23,7 @@ int main (int argc, char const *const *argv)
   s6_svstatus_t status ;
   int flagnum = 0 ;
   int isup, normallyup ;
+  tain_t readytime = TAIN_ZERO ;
   char fmt[UINT_FMT] ;
   PROG = "s6-svstat" ;
   {
@@ -44,22 +45,32 @@ int main (int argc, char const *const *argv)
   if (!s6_svstatus_read(*argv, &status))
     strerr_diefu2sys(111, "read status for ", *argv) ;
 
+  tain_now_g() ;
+  if (tain_future(&status.stamp)) tain_copynow(&status.stamp) ;
+
   {
+    char pack[TAIN_PACK] ;
     struct stat st ;
     unsigned int dirlen = str_len(*argv) ;
-    char fn[dirlen + 6] ;
+    char fn[dirlen + sizeof(S6_SUPERVISE_READY_FILENAME) + 1] ;
     byte_copy(fn, dirlen, *argv) ;
     byte_copy(fn + dirlen, 6, "/down") ;
     if (stat(fn, &st) == -1)
       if (errno != ENOENT) strerr_diefu2sys(111, "stat ", fn) ;
       else normallyup = 1 ;
     else normallyup = 0 ;
+    byte_copy(fn + dirlen, sizeof(S6_SUPERVISE_READY_FILENAME) + 1, "/" S6_SUPERVISE_READY_FILENAME) ;
+    if (openreadnclose(fn, pack, TAIN_PACK) < TAIN_PACK)
+    {
+      if (errno != ENOENT) strerr_warnwu2sys("read ", fn) ;
+    }
+    else
+    {
+      tain_unpack(pack, &readytime) ;
+      if (tain_future(&readytime)) tain_copynow(&readytime) ;
+    }
   }
 
-  tain_now_g() ;
-  if (tain_future(&status.stamp)) tain_copynow(&status.stamp) ;
-  tain_sub(&status.stamp, &STAMP, &status.stamp) ;
-
   isup = status.pid && !status.flagfinishing ;
   if (isup)
   {
@@ -89,8 +100,9 @@ int main (int argc, char const *const *argv)
     buffer_putnoflush(buffer_1small, ") ", 2) ;
   }
 
+  tain_sub(&status.stamp, &STAMP, &status.stamp) ;
   buffer_putnoflush(buffer_1small, fmt, uint64_fmt(fmt, status.stamp.sec.x)) ;
-  buffer_putnoflush(buffer_1small," seconds", 8) ;
+  buffer_putnoflush(buffer_1small, " seconds", 8) ;
 
   if (isup && !normallyup)
     buffer_putnoflush(buffer_1small, ", normally down", 15) ;
@@ -103,6 +115,13 @@ int main (int argc, char const *const *argv)
   if (isup && (status.flagwant == 'd'))
     buffer_putnoflush(buffer_1small, ", want down", 12) ;
 
+  if (readytime.sec.x)
+  {
+    tain_sub(&readytime, &STAMP, &readytime) ;
+    buffer_putnoflush(buffer_1small, ", ready ", 8) ;
+    buffer_putnoflush(buffer_1small, fmt, uint64_fmt(fmt, readytime.sec.x)) ;
+    buffer_putnoflush(buffer_1small, " seconds", 8) ;
+  }
   if (buffer_putflush(buffer_1small, "\n", 1) < 0)
     strerr_diefu1sys(111, "write to stdout") ;
   return 0 ;